He soon followed this up by proposing to Delaware a scheme for the purchase by the government of the seventeen hundred and ninety-eight slaves shown by the census of 1860 to be still held in that State, at the rate of four hundred dollars per capita. A majority of the Lower House of the Legislature of Delaware accepted the idea, but the Senate rejected it and the subject was dropped. But Lincoln did not allow the minds of his antislavery critics to rest. He kept them busy discussing new propositions, and on March 6, 1862, sent a special message to the two Houses of Congress recommending the gradual abolishment of slavery by furnishing to the several States from the public treasury sufficient funds "to compensate for the inconveniences, public and private, produced by such change of system." By this proposition he avoided the objections to the general government interfering with the domestic affairs of the States, and left the people of each State to arrange for emancipation in their own way. "It is proposed as a matter of perfectly free choice with them," he said in his message, and again called attention to the probable effects of the war upon the slave situation. The representatives of the border States in Congress took no heed of the warning, but the Northern papers devoted a great deal of space to a discussion of the proposition, and Lincoln's purpose of giving them something to talk about was accomplished. The most serious objection was based upon the enormous expenses. As early as 1839 Henry Clay estimated the value of the slaves at one billion two hundred and fifty million dollars, and upon the same basis of calculation it must have exceeded two billion dollars in 1860; but Lincoln answered that one-half day's cost of the war would pay for all the slaves in Delaware at four hundred dollars a head, and that eighty-seven days' cost would pay for all the slaves in the border States. He called together the Congressional delegates from the border States and made an earnest effort to convince them of the expediency of his plan. The House of Representatives adopted it by a two-thirds vote, although few of the members from Maryland, Kentucky, and Missouri voted with the affirmative. A month later the resolution was concurred in by the Senate, and what Thaddeus Stevens, the radical leader of the House, described as "the most diluted milk-and-water-gruel proposition ever given to the American people" became a law. It is not necessary to say that the Legislatures of the border States never had an opportunity to take advantage of the proposition; history moved too fast for them. But Lincoln at once began a systematic campaign in Congress to secure legislation for the purchase of all the slaves belonging to loyal owners in the District of Columbia, and that became a law on April 16, 1862.